Girma Tafesse^† , Mitiku Daba, Vedagiri G. Naidu

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-12, 2023, DOI:10.5098/hmt.20.27

Abstract Innovative technologies necessitate extra energy, which can be captured from environmentally sustainable, renewable solar energy. Here, heat and mass transfer through stirring nanofluids in solar collectors for direct absorption of sunlight are pronounced. The similarity transformation served to turn mathematically regulated partial differential equations into sets of nonlinear higher-order ordinary differential equations. These equations have been resolved by the homotopy analysis method manipulating, BVPh2.0 package in Mathematica 12.1. Validations are justified through comparison. Afterward, stronger magnetic field interactions delay the nanofluids mobility. Temperature increases with thermal radiation and Biot numbers. Entropy formation and nanoparticle concentration dwindle when Schmidt’s number surges. More >

Yangyang Tian^a , Zhuo Chen^b,* , Qi Zhuang^c

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-11, 2023, DOI:10.5098/hmt.20.26

Abstract The cyclone separator has remarkable amplification effect, which is an important factor affecting its separation efficiency and pressure drop. The numerical simulation of Stairmand cyclone separators with cylinder diameters of 200, 280, 400, 480 and 600mm after geometric similarity amplification was carried out by ANSYS software. RSM model was used for gas phase and DPM model was used for particle phase. The results show that after the cyclone size is enlarged geometrically, the tangential velocity tends to increase with the increase of the cyclone barrel diameter at the same inlet gas velocity, which leads to the increase of turbulence energy… More >

Le Anh Duc^a , Pham Van Kien^b,*, Nguyen Thanh Tan^b, Doan Thanh Son^b, Nhanh Van Nguyen^c, Ngoc Xuan Nguyen^d

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-6, 2023, DOI:10.5098/hmt.20.25

Abstract This study focused on the heat and mass transfer in radio (RF) assisted heat pump (HP) drying of carrots. The experimental drying of carrot by RF assisted HP drying method was conducted to evaluate the effect of RF power on drying efficiency including drying rate and heating rate. The input drying parameters were drying air temperature of 45oC, drying air velocity of 2.5 m/s and RF power of 0, 0.5 and 1.5 kW, in which, RF power of 0 was corresponding to HP drying method. The experimental drying results showed that in RF assisted HP drying method, the drying rate… More >

Xiaoyong Gu^a,*, Gang Wu^b, Biwen Chen^c

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-9, 2023, DOI:10.5098/hmt.20.24

Abstract To maintain the maximum temperature and temperature difference of batteries in electric vehicles within a reasonable range, a battery thermal management system combining closed air-cooling with phase change material(PCM) is proposed and investigated. A three-dimensional numerical model is developed and validated by experiment. The results indicate that the temperature rise of batteries decreases with the increase of ambient temperature. The increasing filling amount of PCM reduces the maximum temperature difference of batteries as well as the effect of the airflow rate on maximum temperature of batteries. The energy consumption is minimum when the filling amount of PCM is 0.28kg. More >

Mohamed Shaimi^* , Rabha Khatyr, Jaafar Khalid Naciri

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-14, 2023, DOI:10.5098/hmt.20.23

Abstract This paper presents an exact analytical solution to the extended Graetz problem in microchannels and microtubes, including axial heat conduction, viscous dissipation, and rarefaction effects for an imposed constant wall temperature. The flow in the microchannel or microtube is assumed to be hydrodynamically fully developed. At the same time, the first-order slip-velocity and temperature jump models represent the wall boundary conditions. The energy equation is solved analytically, and the solution is obtained in terms of Kummer functions with expansion constants directly determined from explicit expressions. The local and fully developed Nusselt numbers are calculated in terms of the Péclet number,… More >

Feng-Lin Zhou^a , Kai-Yuan Zhang ^a, Liang Cheng^b,† , Hai-Bing Cai^c, Yu-Liang Zhang^b, Min-Feng Lv^d

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-10, 2023, DOI:10.5098/hmt.20.22

Abstract In order to grasp the reverse startup characteristics of a small radial vane pump in the case of misoperation, a circulation piping system that includes the pump is established. Numerical simulation of the full three-dimensional unsteady incompressible viscous flow is performed based on the slip-grid technique and user-defined functions (UDF). According to the results, the static pressure fluctuation is small at the inlet of the centrifugal pump during the reverse startup, which differs significantly from the forward startup. Compared to the impeller rotational speed, the time required for the shaft power, head and flow curves to reach stability is lagged,… More >

Ghaith Yahya Abusaibaa^a , Kamaruzzaman Sopian^a,*, Hasila Jarimi^a , Adnan Ibrahim^a, Saffa Riffat^b

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-6, 2023, DOI:10.5098/hmt.20.21

Abstract This study will demonstrate the performance of a photovoltaic (PV) powered vapour compression cooling system connected to a Phase Change Material (PCM) storage tank. Three options were studied, namely (a) PV vapour compression with a PCM storage tank and an air-conditioned room with chilled water circulation with transparent membrane/desiccant; (b) PV vapour compression with a PCM storage tank and an air-conditioned room with chilled air dehumidification; and (c) PV vapour compression with a PCM storage tank and an air-conditioned room chilled by combined water circulation, a transparent membrane/desiccant, and air duct dehumidification. Simulation using TRNSYS, TRNBuild, and EES programmes has… More >

Qais Abid Yousif^a , Omar Rafae Alomar^a,*, Obed M. Ali^b , Omar Mohammed Ali^c

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-14, 2023, DOI:10.5098/hmt.20.20

Abstract This work involves a numerical investigation on free convection heat transfer occurred by a hot cylinder immersed in a square duct cooled from one side under different temperatures. Simulations have been done for a large ranges of Rayleigh number (10³ ≤ Ra ≤10⁷ ) and right wall temperature (0≤T_r ≤0.75). The results displayed that Nu is enhanced with rising in Ra and decreasing in T_r. The value of Nu is decreased with rising in T_r, where the maximum reduction in Nu is about 32% for T_r=0.75 as compared to T_r=0. The maximum enhancement range for Nu is found between 50%… More >

Xuehui Jing^a,* , Wei Li^a, Zhaoyu Li^a , Zhiyun Wang^b

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-4, 2023, DOI:10.5098/hmt.20.19

Abstract This paper numerically simulates the combustion in a 300MW tangentially fired pulverized high-alkali coal boiler under low-load conditions. The combustion process, temperature distribution and the thermal load in the furnace at different height are analyzed under three different load conditions, which are 30%, 45% and 60% of full load. The temperature distribution and the variation of NO_x concentration under different load conditions are investigated, as well. The results show that the combustion processes of pulverized high-alkali coal in the furnace are similar under different load conditions, but the positions of the fuel’s full combustion are related to the loads. With… More >

Ameer Abed Jaddoa^* , Karema Assi Hamad, Arshad Abdul Jaleil Hameed

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-9, 2023, DOI:10.5098/hmt.20.18

Abstract In the Heat Transfer process, many innovations were introduced aiming to obtain the most optimum behavior of the cooling process using nanofluids as coolant liquids. These nanofluids have gained much attention in cooling systems due to their special rheological and thermal performance. In this work, an experimental evaluation is conducted for nanofluids Al₂O₃, SiO₂, CuO, ZnO, and TiO₂ nanoparticles applied to a mini-channel. The nanofluid particles were entirely spread out in purified water (size of 15 nm) before being passed to the heat sink through a confined inflow channel. The obtained results showed that the achieved improvement rates are 25%,20%,… More >